Adaptive Sanding Head Force Control for Compliant Workpieces
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Solution Overview
Problem
Automated finishing systems face challenges in efficiently processing workpieces with varying compliance characteristics, as high target forces can damage compliant regions while low forces result in slow material removal and inconsistent contact, leading to poor surface finish and increased processing time.
Innovation Solution
The system autonomously scans a workpiece to create a virtual model, defines regions by compliance characteristics, and adjusts target forces in real-time based on deflection data to maintain optimal contact and material removal rates, using a robotic arm with a sanding head and optical sensors to navigate and process the workpiece.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high target forces are applied during automated finishing, then material removal rate is improved, but compliant regions of the workpiece are damaged
Solution Approach 1:
The system applies different target forces to different regions of the workpiece based on their compliance characteristics. The controller divides the workpiece into regions with varying compliance and assigns appropriate force levels to each region, allowing high forces on rigid areas for fast material removal while using low forces on compliant areas to prevent damage.
Solution Approach 2:
The system dynamically adjusts the target force in real-time based on measured deflection data. The controller continuously monitors workpiece deflection during processing and modifies the target force accordingly, increasing force when deflection is within acceptable ranges and reducing force when compliant regions are detected, thereby optimizing both productivity and reliability.
2Reliability
If low target forces are applied during automated finishing, then workpiece damage is prevented, but material removal rate decreases and processing time increases
Solution Approach 1:
The system applies different target forces to different regions of the workpiece based on their compliance characteristics. The controller divides the workpiece into regions with varying compliance and assigns appropriate force levels to each region, allowing high forces on rigid areas for fast material removal while using low forces on compliant areas to prevent damage.
Solution Approach 2:
The system dynamically adjusts the target force in real-time based on measured deflection data. The controller continuously monitors workpiece deflection during processing and modifies the target force accordingly, increasing force when deflection is within acceptable ranges and reducing force when compliant regions are detected, thereby optimizing both productivity and reliability.
3Ease of operation
If constant target force is applied during automated finishing, then system operation is simplified, but surface finish quality deteriorates due to inconsistent contact
Solution Approach 1:
The system dynamically adjusts the target force in real-time based on measured deflection data. The controller continuously monitors workpiece deflection during processing and modifies the target force accordingly, increasing force when deflection is within acceptable ranges and reducing force when compliant regions are detected, thereby optimizing both productivity and reliability.
Solution Approach 2:
The system uses deflection sensors to provide real-time feedback on workpiece compliance and adjusts the target force based on this feedback. The controller creates a closed-loop control system where deflection measurements inform force adjustments, ensuring consistent contact and surface quality while maintaining simple automated operation.
4Ease of manufacture
If uniform processing parameters are used across the entire workpiece, then programming and setup are simplified, but processing time increases due to inefficient material removal from rigid regions
Solution Approach 1:
The system applies different target forces to different regions of the workpiece based on their compliance characteristics. The controller divides the workpiece into regions with varying compliance and assigns appropriate force levels to each region, allowing high forces on rigid areas for fast material removal while using low forces on compliant areas to prevent damage.
Solution Approach 2:
The system dynamically adjusts the target force in real-time based on measured deflection data. The controller continuously monitors workpiece deflection during processing and modifies the target force accordingly, increasing force when deflection is within acceptable ranges and reducing force when compliant regions are detected, thereby optimizing both productivity and reliability.
Data Source
AI summary
One variation of a method includes: accessing a maximum deflection distance of a workpiece; defining a first workpiece region characterized by a first compliance range; defining a second workpiece region characterized by a second compliance range greater than the first compliance range; assigning a nominal target force to the workpiece; navigating a sanding head across the first workpiece region during a processing cycle; driving the sanding head below a virtual unloaded surface of the workpiece stored in the virtual model to maintain forces, of the sanding head on the first workpiece region, approximating the nominal target force; calculating a maximum offset between the positions of the sanding head in the first workpiece region and the virtual unloaded surface; and, in response to the first maximum offset approaching the maximum deflection distance, assigning a lower target force to the second workpiece region of the workpiece.